Digital communication is well known in the art. One well known communication standard which is proposed and in some areas is being implemented is the ISDN network standard. The ISDN network standard is a digital communication protocol for a public network (such as one operated by local telephone companies). In the United States, the ISDN network is a digital communication network operating at the rate of 64 kilobits per second per channel.
Computers are well known in the art. Typically, however, they operate at a much higher frequency than a single channel of a public communication network. Thus, for example, computers can store and retrieve at the rate of millions of bits per second.
As it becomes increasingly desirable to connect computers directly onto public digital communication networks, such as an ISDN network, methods and apparatuses must be provided to interface the computer with the communication network. One prior art technique is disclosed in U.S. Pat. No. 4,775,987. In that patent, a single digital data stream from a source (such as a computer) is supplied to a distributor which supplies a portion of the data cyclically onto a plurality of channels. Each of the channels operates at a rate slower than the rate of the single stream of data supplied to the distributor. In this manner, the transmission of data over the plurality of channels, in total, is or exceeds the rate of the single stream of digital data from the source to the distributor. In that patent, however, once a communication session has begun, the number of channels used for the communication session is fixed and is not varied until the communication session is terminated.
In U.S. Pat. No. 4,805,167, a technique is disclosed whereby once a communication session has begun, the number of channels used for the communication session can be varied. However, it is believed that this technique depends upon the supplier of the digital data to inform its receiver to change the number of channels during the communication session. Accordingly, it is desirable to provide an automatic method and apparatus for dynamically changing the bandwidth or the number of channels in a digital communication session.
Other prior art include: U.S. Pat. Nos.: 4,759,017; 4,899,337; 4,893,305; 4,888,765; 4,864,567; 4,825,434; 4,980,886; 4,987,570; and 4,903,261.